GRASSES OF IOWA. 239 



had no difficulty in getting fresh spores to germinate abun- 

 dantly in twenty-four hours. The promycelium is slender and 

 bears nar.ow^, elliptical bodies called sporidia, which later 

 cause the infection of the plant. The spores also germinate 

 readily in normal nutrient solution, frequently budding. Bre- 

 feld observed that the sporidia, when transferred to a nutrient 

 solution, continued to form sporidia. He obtained these yeast- 

 like spores for many generations. 



Manner of infection. — Infection in this smut is probably by 

 way of the seed. Wolff, in his classic experiments, found that 

 smuts entered through the first formed leaves. Bref eld's 

 classic experiments also indicate that infe3tion takes place dur- 

 ing the early stages of the germination of oats. 



Jensen thinks that smut do3S not enter with barnyard 

 manure, and he supports it by some evidence: 



1885. 1886 



Barnyard manure plot 42 smutted heads 1.2 per cent smutted. 



Artificial manure plot 35 smutted heads 1.0 percent smutted 



He furthermore suggests that infection is brought about by 

 spores contained in the husks which lodged there while the 

 oats were in flower, but this is contrary to the usual experience. 

 Kellerman and Swingle state: "In an experiment of ours in 

 June, 1888, a square rod of oats just in blossom were dusted 

 with smut spores in considerable quantity on the 20th, 22d, 

 25th and 27th of the month. When ripe it was harvested and 

 kept separate In the spring of 1889 it was planted, together 

 with other plots, with seed from other parts of the same field. 

 One of the artificially infected plots (23) was 6.8 per cent smut- 

 t3d, and the other was 5.36 per cent, while the untreated plot 

 had 6.4 per cent of smut, midway between the two artificially 

 smutted ones. " 



Damage and distribution. — The damage done by this smut is 

 very large. Arthur gives the following percentages in differ 

 ent varieties grown at Geneva, N. Y. : "J. C. Arthur, in 1884, 

 gave the results of counts of oats grown on the farm of the New 

 York Agricultural Experiment Station at Geneva, N. Y., and 

 found American Triumph, of 1,237 heads counted, had 10 per 

 cent smutted." 



Arthur* estimates the loss for Indiana at 8797,526. Jonest 

 examined 35,177 heads for oats smut; the average smut in 1892 



*L';ose Smut of Oats. Bull. Purdue Univ. Agrl. Exp. Sta. 35: 83. 

 +Aanual Report of Vermont Agrl. Exp. Sta. 6: 73-83. 



